<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Flowing button</title>
    <style>
      body {
        background-color: #000000;
      }
      a {
        text-decoration: none;
        position: absolute;
        left: 50%;
        top: 50%;
        transform: translate(-50%, -50%);
        font-size: 24px;
        text-transform: uppercase;
        background: linear-gradient(90deg, #009ef8, #fd5aa5, #ffe42e, #009ef6);

        width: 400px;
        height: 100px;
        color: #ffffff;
        line-height: 100px;
        text-align: center;
        border-radius: 50px;
        background-size: 400%;

        z-index: 1;
        
      }

      a:hover{
        animation: identifier 5s infinite linear;
      }

      a::before{
        content: "";
        position: absolute;
        left: -5px;
        right: -5px;
        top: -5px;
        bottom: -5px;
        background: linear-gradient(90deg, #009ef8, #fd5aa5, #ffe42e, #009ef6);
        border-radius: 50px;
        background-size: 400%;
        filter: blur(20px);
        z-index: -1;
      }

      a:hover::before{
        animation: identifier 5s infinite linear;
      }

      /* a::before:hover{
        animation: identifier 5s infinite linear;
      } */

      @keyframes identifier {
        100%{
          background-position: -400% 0;
        }
      }



    </style>
  </head>
  <body>
    <a href="javascript:;">Flowing button</a>
  </body>
</html>
